Health

The role of ultrasound in evaluation of patients with elevated maternal serum alpha-fetoprotein: a review

Article Abstract:

Elevated maternal serum alpha-fetoprotein (MSAFP) levels early in pregnancy are an indication of fetal deformities such as spina bifida. The levels that indicate fetal problems and those that are normal overlap, so that finding a high MSAFP level is only an indication that other tests should be performed. Amniotic fluid alpha-fetoprotein (AFP) levels are more precise in diagnosing fetal abnormalities, but require amniocentesis. This procedure involves puncturing the amniotic sac to obtain fluid for testing. It poses a danger to the fetus and should only be used when abnormalities are highly probable. Ultrasound (US), an imaging technique that uses high energy sound waves, may provide an intermediate step between finding an elevated MSAFP level and performing amniocentesis. US can detect intracranial changes in the fetus that are highly indicative of spina bifida. Anencephaly, a severe defect in which the fetal brain only consists of a brain stem and some basal ganglia, occurs in half the cases of spina bifida. Almost all cases of anencephaly can be detected by US. Other intracranial defects indicative of spina bifida can also be detected by US. These include a small biparietal diameter (BPD, the diameter of the intracranial cavity), ventriculomegaly (enlarged brain ventricles), obliteration of the cisterna magna (a reservoir in the brain), and an abnormally shaped or absent cerebellum. Abnormal US findings may also be indicative of genetic abnormalities. When US findings are abnormal, amniocentesis should be performed to obtain samples for genetic screening, even when MSAFP levels are normal. The risks associated with amniocentesis include a 0.5 percent chance of pregnancy loss (miscarriage). Using ultrasound to screen women for fetal abnormalities and detecting fetal abnormalities with this technique reduce the need for amniocentesis and help in deciding if it should be performed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Fetal responses to maximal swimming and cycling exercise during pregnancy

Article Abstract:

Many studies have concluded that moderate exercise during an uncomplicated pregnancy may be beneficial for the mother, but limited information is available about the effect of maternal exercise on the developing fetus. A study was designed to examine the effects of swimming and cycling at maximal (vigorous) intensity on the fetal heart rate and uterine and umbilical blood flow. Thirteen women between the ages of 24 and 34 years (average age 30 years) participated in both cycling and swimming at 25 weeks and again at 35 weeks gestation. For comparison, fetal heart rates and blood flow parameters were measured before exercise, immediately after exercise, and at five-minute intervals for 20 minutes after exercise. The average maternal maximal heart rate was 179 beats per minute and was not significantly different for cycling versus swimming. The average fetal heart rate decreased slightly just after exercise, and then increased to levels above baseline at 10 to 20 minutes after exercise. Changes in fetal heart rate were larger after cycling than after swimming. Fetal heart rate changes were apparently responsible for short-term changes observed in umbilical blood flow. It is concluded that maternal exercise at a maximal level leads to transient fetal bradycardia (slowed heart rate) in about 15 percent of fetuses, and this is more common after cycling than swimming. All subjects delivered full-term healthy infants. It is difficult to determine the relative importance of the changes in fetal heart rate due to exercise during pregnancy, but the authors suggest that they probably carry little clinical significance if the pregnancy is uncomplicated. (Consumer Summary produced by Reliance Medical Information, Inc.)

Monozygotic twins discordant for partial trisomy 1

Article Abstract:

Monozygotic twins develop from the same fertilized egg, which divides at an early stage to become two embryos. Although such twins are usually identical, genetic alterations that occur after the division into two embryos can result in discordant (genetically different) individuals. A case of twins discordant for a genetic defect, partial trisomy 1, is presented. The infants were delivered by cesarean section after 30 weeks' gestation. The larger infant had many abnormalities and died 30 minutes after birth; it was affected by partial trisomy 1 (an abnormality caused by translocation, or movement, of genetic material). The other infant had a normal karyotype (chromosomal arrangement) and developed normally. The name for genetic discordance in monozygotic twins is ''heterokaryotype''; a brief discussion of this rare condition is provided. The abnormal twin was a mosaic; not all cells of its body contained the mutation. (Consumer Summary produced by Reliance Medical Information, Inc.)